JPH05134295A - Diopter adjustment device for finder device - Google Patents

Abstract

(57) [Abstract] [Purpose] In the viewfinder device, the imaging position of the objective optical system changes due to temperature and humidity changes, component precision errors, and assembly errors, and the diopter adjustment mechanism on the eyepiece optical system side alone Based on the discovery that the clear image and the field frame cannot be observed at the same time, or that the diopter adjustment becomes impossible if the image position of the objective optical system deviates significantly, To obtain a viewfinder device that can surely adjust the diopter even if there are some errors. A finder device having an objective optical system and an eyepiece optical system, wherein a finder device is provided with an objective-side imaging position adjusting means for adjusting an imaging position by the objective optical system.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a finder device used in a camera, and more particularly to a diopter adjusting device for the finder device.

[0002]

2. Description of the Related Art A finder apparatus has a basic structure in which an object image formed by an objective optical system is observed by an eyepiece optical system. Recently, in this finder device, some or all of the constituent lenses have been made of resin in order to reduce the weight and cost. However, when the temperature and / or humidity rises, the resin lens has an unavoidable property that the radius of curvature increases due to thermal expansion or moisture absorption and the refractive index decreases. Further, particularly in a real image type finder in which the objective optical system has a positive power, a lens having a strong power tends to be used as a constituent lens group in order to achieve compactness, and a lens having a strong power has a shape and a refractive index. Changes in the optical performance significantly change. In particular, since a variable magnification finder uses a large number of lenses, there is a possibility that a diopter shift may occur due to an error in component accuracy or an assembly error in the manufacturing process. For this reason, the position of the object image formed by the objective optical system may largely change from the position of the field frame, which may cause a phenomenon in which the viewfinder is poorly viewed.

Although many finder devices generally have a diopter adjustment mechanism, the conventional diopter adjustment mechanism adjusts the diopter of the eyepiece optical system. However, even if this conventional diopter adjustment mechanism allows the focus position of the eyepiece optical system to match the position of the image formed by the objective optical system, the position of the image formed by the objective optical system and the position of the field frame do not shift. Occurs and the field of view frame is blurred. That is, it has been found that there is a problem that a clear field frame and an object image cannot be observed at the same time. Further, when the position of the image by the objective optical system changes greatly, the diopter adjustment mechanism of the eyepiece optical system cannot adjust the diopter and the object image itself cannot be clearly observed. This problem is particularly noticeable when the constituent lens is a resin lens.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a viewfinder device with a diopter adjusting mechanism on the eyepiece optical system side because the image forming position of the objective optical system changes due to temperature and humidity changes, component precision errors and assembly errors. Based on the discovery that the clear image and the field frame cannot be observed at the same time, or that the diopter adjustment becomes impossible if the image position of the objective optical system deviates significantly, An object of the present invention is to obtain a finder device capable of surely adjusting diopter even if there is such an error.

[0005]

SUMMARY OF THE INVENTION The present invention is characterized in that, in a finder apparatus having an objective optical system and an eyepiece optical system, it has objective-side image-forming position adjusting means for adjusting the image-forming position of the objective optical system.

The present invention can theoretically be applied to both a real image type finder apparatus in which the objective optical system has a positive power and an inverse Galilean type finder in which the objective optical system has a negative power. However, as described above, the usefulness of the present invention is high for the real image type finder device in which a lens having a strong power tends to be used for the constituent lens group of the objective optical system having a positive power as a whole. The real image type finder device has a field frame on the image plane of the objective optical system, and it is necessary to adjust so that an object image is formed on this field frame.

[0007]

The present invention will be described below with reference to the illustrated embodiments.
First, with reference to FIG. 21, the location of the problem of the finder device to be solved by the present invention will be clarified. FIG. 21 shows an objective optical system 10 and an eyepiece optical system 11 in the real image type finder device.
The state of diopter change due to is schematically shown. At the image forming position of the object at the standard distance by the objective optical system 10, the visual field frame 12
Is placed, and the observer observes an image of the object by the objective optical system 10 and the field frame 12 via the eyepiece optical system 11. Focus positions (image forming positions) O ₁₁ and O ₁₂ of the designed objective optical system 10 and the eyepiece optical system 11 coincide with the field frame 12, as indicated by the solid line. The objective optical system 10 for some reason
When the focal length of the eyepiece optical system 11 is extended, the ideal designed focal positions O ₁₁ and O ₁₂ do not coincide with the field frame 12, and the focal positions O ₁₁ ′ and O ₁₂ ′ shown by broken lines in the figure become.
Such a change in the focal length is caused by, for example, a change in temperature and / or when the lens forming the finder is a resin lens.
When the humidity increases, the radius of curvature increases due to thermal expansion or moisture absorption, and the refractive index decreases. The figure exaggerates the state in which the focal length is longer than the design value.

The conventional diopter adjustment does not consider the change of the focal position of the objective optical system 10. Speaking of diopter adjustment, the focal position of the eyepiece optical system 11 is changed according to the diopter of the observer. Was only. However, when the focal position of the objective optical system 10 changes significantly, the position of the image changes greatly from the position of the field frame 12, and the image and the field frame cannot be clearly recognized at the same time, and the eyepiece optical system 11 A situation may occur in which a clear image cannot be visually recognized only by adjusting the diopter.

The present invention is characterized in that an objective-side image forming position adjusting means (hereinafter referred to as a position adjusting means) is provided on the objective optical system 10 side in order to solve such a conventional problem. It is a thing. 1 and 2 show a first embodiment of the present invention. In this embodiment, the present invention is applied to a real image type zoom finder device. The objective optical system 10 includes a fixed lens L1, movable lenses L2 and L3 for zooming, and a mirror 13, and a field frame 12 is provided at an image forming position of an object at a standard distance by the objective optical system 10. Behind the field frame 12, a Porro prism P for inverting the vertical and horizontal directions of the object image by the objective optical system 10 is provided.
The eyepiece optical system 11 is located behind the.

As shown in FIG. 2, the mirror 13 is flat at room temperature (design temperature), has no power, and acts as a convex lens when the temperature and / or humidity rises, and constitutes a mirror surface. And a substrate 13b attached to the reflecting member 13a and having a different coefficient of thermal expansion from the reflecting member 13a. Board 13
For example, b is a synthetic resin substrate, on which a substrate 13b made of aluminum can be coated. Since the synthetic resin has a coefficient of thermal expansion about three times that of aluminum and expands when it absorbs moisture, the reflecting member 13a becomes concave when the temperature and / or humidity rises. Since the concave mirror has a positive power, when the focal length of the objective optical system 10 is going to be extended, the concave mirror acts in a direction to reduce the focal length. Therefore, it is possible to form an object image by the objective optical system 10 on the field frame 12 regardless of changes in temperature and humidity.

FIG. 3 shows a second embodiment of the present invention. In this embodiment, even if the focal length of the objective optical system 10 changes by adjusting the optical path length of the objective optical system 10,
The position of the object image by the objective optical system 10 can be adjusted on the field frame 12. In the objective optical system 10, a movable prism 15 (movable reflecting member) is arranged between the fixed mirror 13A and the field frame 12. The movable prism 15 has two total reflection surfaces 15a for refracting the optical path in the same direction by 90 °. Therefore, when the movable prism 15 is moved in the direction of arrow A, the optical path length of the objective optical system 10 is increased. Change. Therefore, when the focal length of the objective optical system 10 is extended, if the movable prism 15 is moved and adjusted in the direction in which the optical path length becomes long, the object image by the objective optical system 10 can be formed on the field frame 12.

FIG. 4 shows a fixed lens L of the objective optical system 10.
2 is a schematic diagram of an example in which the focal position of the objective optical system 10 is adjusted by moving 1 and the entire movable lenses L2 and L3 in the optical axis direction. The fixed lens L1 and the movable lenses L2 and L3 are supported on an adjustment frame 16 that can be moved in the optical axis direction independently of the zooming mechanism. Movement adjusting means). Therefore, when the focal length of the objective optical system 10 is extended, the object image by the objective optical system 10 can be formed on the field frame 12 by moving and adjusting the adjustment frame 16 by the position adjusting means 17.

FIG. 5 is a schematic diagram of an embodiment in which the focal position of the objective optical system 10 is moved by moving only a specific lens of the constituent lens groups of the objective optical system 10. The fixed lens L1 and the movable lenses L2 and L3 are respectively provided with position adjusting means 18 (specific lens movement adjusting means) in the optical axis direction, and the position can be adjusted independently. Fixed lens L1 and movable lenses L2, L
The amount of change (sensitivity) of the focal position with respect to the position adjustment amount in the optical axis direction of No. 3 differs depending on the lens group. Each objective optical system 10 determines which lens group is moved to compensate for the change in the focal position of the objective optical system 10.

Next, the influence of the change in the focal length of the objective optical system and the eyepiece optical system of the real image type zoom finder on the diopter will be described. 6 and 7 show a fixed lens L101,
Movable variable power lens L102 (L103), fixed lens L1
05 and field lens L106
And a real image type finder device including the eyepiece optical system 11 including the eyepiece L108 in a wide state and a tele state.

FIG. 8 and FIG. 9 are graphs in which the influence of the focal length of the constituent lenses of the real image type finder device on the diopter at the wide end and the tele end when the focal length is extended by 1% is examined. In this graph, when the diopter does not deviate from the design value (−1 diopter), “0” is set and the influence of each lens on the diopter is quantified. From this graph, the lens having a great influence on the diopter is found to be the objective optical system 10.
Concentrate on, lens with strong power (eg L1
02), it can be seen that the change in focal length has a large effect on the diopter, and that the same lens has different effects on the diopter between the wide side and the tele side.

FIG. 10 and FIG. 11 are graphs similarly examined for the influence on the diopter when each lens group is moved by 1 mm toward the eye side in the optical axis direction. This graph is
As described with reference to FIGS. 8 and 9, even with the same lens in the objective optical system 10, the influence of the change in the position on the diopter is different between the wide side and the tele side. That is, when the same lens changes its position in the optical axis direction, the sensitivities on the wide side and the tele side are different.

In the embodiment for adjusting the diopter by moving the specific lens group in FIG. 5, the position of each lens group is adjusted in consideration of the sensitivity given to the diopter adjustment of each constituent lens group. be able to. At that time, it is not always necessary to adjust both the telephoto and the wide angle, and for example, the diopter on the telephoto side may be adjusted to a design value, and a slight deviation of the diopter on the wide side may be ignored. This is a feature of the finder device that can be expected to have an accommodating effect on the eye, and is different from a photographic optical system that must be in exact focus at all focal lengths.

12 to 15 show an embodiment (fifth embodiment) of a finder device showing a specific position adjusting means of the present invention. In this embodiment, the present invention is applied to a real image type zoom finder device. 12
[FIG. 3] is a view showing an optical system configuration of a finder. FIG. 13 is a schematic perspective view of a finder showing an embodiment of the present invention. As shown in FIGS. 12 and 13, the objective optical system includes a first movable objective lens 202 fitted in a first lens frame 209 (lens frame body) and a second movable objective lens fitted in a second lens frame 211. 203, a third movable objective lens 204, a mirror 205, and a fixed objective lens 206. Behind the fixed objective lens 206, a Porro prism 207 which reverses the vertical and horizontal directions of the object image by the objective optical system is provided. At the image forming position of the object at the standard distance by the objective optical system, here, the Porro prism 20 on the rear surface of the fixed objective lens 206 is used.
A field frame 207b is drawn on the surface 207a of No. 7. Behind this Porro prism 207 is the eyepiece 2 of the eyepiece optical system.
08 is located.

As shown in FIG. 15, a hole 211a is formed in the second lens frame 211 in a direction parallel to the optical axis, and a pin 211b facing downward in the figure is formed in the lower part. Figure 1
3, the pin 211b is not shown because it is behind other elements. The second lens frame 211 has the hole 2
11a is fitted to the guide shaft 212a and is supported so as to be movable in the optical axis direction. On the other hand, the first lens frame 209 is
A hole 209a formed in the frame is fitted to a guide shaft 212b parallel to the guide shaft 212a, and is supported so as to be movable in the optical axis direction. The first lens frame 209 has an arm 209b protruding on its side surface, and an internal thread 209c is formed on the arm 209b. A fine adjustment male screw 214 is screwed into the female screw 209c. Further, the guide case portion 209d is provided on the side surface of the first lens frame 209.
Is equipped with. This guide case portion 209d is shown in FIG.
Movable element 210 (driven member) having a pin 210a shown in FIG.
Is formed so that the movable element 210 can be moved in the optical axis direction of the finder. A biasing spring 219 (illustrated by a broken line) shown in FIG. 14 is first inserted into the guide case portion 209d, and then the movable element 210 is inserted therein.

Further, the first and second lens frames 209, 2
As means for moving both frames of 11 in the optical axis direction,
A lens frame drive cam plate 215 (variable magnification means) as shown in FIG. 13 is provided. The lens frame drive cam plate 215 is provided with two cam grooves 215a and 215b, and the cam frame 215a has the pin 21 of the lens frame 211.
In the cam groove 215b, the pin 210a of the movable element 210 provided in the lens frame 209 is in sliding contact with the inner surface of each cam groove 1b.

The front and rear ends of the guide shafts 212a and 212b are respectively supporting members 218a and 218b.
It is fixed to the camera body 201 via. Also,
Pin 21 corresponding to the first and second lens frames 209 and 211
0a and 211b are cam grooves 2 of the lens frame drive cam plate 215.
The support member 218a of the guide shaft 212a is configured so as to surely come into sliding contact with one of the inner surfaces of the grooves 15b and 215a.
A biasing spring 213a is inserted between the second lens frame 211 and the second lens frame 211, and the support member 21 of the guide shaft 212b is also provided.
A biasing spring 213b is fitted and inserted between 8a and the first lens frame 209. The lens frame drive cam plate 215 is provided with a gear 215c at one end thereof, and the cam drive gear train 21
6 is engaged with the drive motor 217.

With this structure, the lens frame drive cam plate 21
By moving 5 in the direction of the arrow shown in FIG. 13, the first movable objective lens 202, the second movable objective lens 203, and the third movable objective lens 204 of the finder move in the optical axis direction, and zooming is performed. It Cam grooves 215a and 215b provided in the lens frame drive cam plate 215
Is designed so that a normal zooming operation is performed, and during zooming, the image at the standard object distance is always at the position of the field frame 207b.

The diopter adjustment of the objective optical system is performed as follows. The movable element 210 and the first lens frame 209 relatively move in the optical axis direction by turning the fine adjustment male screw 214 that abuts on the front surface pressed portion 210b of the movable element 210. As a result, the position of the movable element 210 is set to the cam groove 2
15b, and the position of the first lens frame 209 with respect to the movable element 210 is determined by adjusting the fine adjustment male screw 214. Therefore, when the distance between the first movable objective lens 202, the second movable objective lens 203, and the third movable objective lens 204 is changed, the change amount of the distance is kept constant, and the diopter on the objective side. Adjustments can be made. That is, in the present embodiment, when the position of the image of the objective optical system is displaced from the position of the field frame 207b, it can be corrected and the image position can be positioned on the same plane as the field frame 207b. Becomes

16 to 20 show another embodiment (sixth embodiment) different from the fifth embodiment of the finder apparatus showing the specific position adjusting means of the present invention. .. The same members as those constituting the finder of the fifth embodiment are designated by the same reference numerals. FIG. 16 is a schematic perspective view of a finder showing an embodiment of the present invention. As shown in FIG. 16, the objective optical system includes a first movable objective lens 202 fitted in a lens frame 310 (lens frame body), a second movable objective lens 203 fitted in a lens frame (not shown), and a third movable objective lens. The lens 204, the mirror 205, and the fixed objective lens 206 are provided. Behind the fixed objective lens 206, a Porro prism 207 which reverses the vertical and horizontal directions of the object image by the objective optical system is provided. A field frame 207b is drawn on the surface 207a of the Porro prism 207 on the side of the fixed objective lens 206, at the image forming position of the object at the standard distance by the objective optical system. An eyepiece lens 208 of an eyepiece optical system is located behind the Porro prism 207.

As shown in FIG. 16, the lens frame 310 in which the first movable objective lens 202 is fitted is movable in the optical axis direction in the lens frame guide groove 309a of the lens frame holder 309 provided in the camera body (not shown). Fit in.
A sliding member guide groove 310a, into which a sliding member 311 as an adjusting means is fitted and which holds the sliding member 311 movably in a direction orthogonal to the optical axis, is formed on the upper portion of the lens frame 310.

As shown in FIG. 17, the sliding member 311 has a hole 311a formed at the center of the circular portion at one end thereof. Further, a fan-shaped step portion 311b is formed in the hole 311a along with the hole 311a. And the hole 311
The cylindrical portion 312a of the driven member 312 shown in FIG. 18 is press-fitted into a. The cylindrical portion 312a of the driven member 312
Is fitted into the hole 311a with a frictional resistance R equal to or greater than a certain value in the circumferential direction. That is, the cylindrical portion 312a of the driven member 312.
Is inserted into the hole 311a so as to rotate when a force larger than the frictional resistance R is applied in the circumferential direction of the cylindrical portion 312a, and the driven member 312 can rotate within the range of the fan-shaped step portion 311b. Is.

The linear guide plate 313 shown in FIG. 16 is provided with a linear guide groove 313a, and the sliding portion 312b of the driven member 312 is in sliding contact with the inner surface of the linear guide groove 313a. As a result, the linear guide plate 313 is moved to the driven member 31.
2 guides the movement in the optical axis direction. Further, the linear guide plate 313 is fixed to the lens frame holder 309, and also plays a role of preventing the lens frame 310 from coming off the lens frame holder 309 when the lens frame 310 moves in the optical axis direction. Projection portion 310b of lens frame 310
Like the sliding portion 312b, is in sliding contact with the inner surface of the straight guide groove 313a.

Lens frame drive cam plate 31 as a zooming means
4 has a cam groove 314a.
The sliding portion 312b of the driven member 312 is in sliding contact with the inner surface of a. Further, the lens frame drive cam plate 314 is, in the same way as the lens frame drive cam plate 215 in the fifth embodiment, driven by a drive motor (not shown) through a gear train (not shown) in a direction intersecting the optical axis. Driven to. Therefore, when the lens frame drive cam plate 314 is driven in the direction of the arrow shown in FIG. 16, the driven member 312, the sliding member 311, and the lens frame 310.
The first movable objective lens 202 moves in the optical axis direction via. The lens frame drive cam plate 314 also has a cam groove 314a.
Another cam groove (not shown) is provided, and the cam groove also drives the second movable objective lens 203 and the third movable objective lens 204 via some intermediate member (not shown).

With this structure, the lens frame drive cam plate 3
By driving 14 the first movable objective lens 202 and the second movable objective lens 203 of the finder,
The third movable objective lens 204 moves in the optical axis direction and zooming is performed. A cam groove 314a provided on the lens frame drive cam plate 314 and another cam groove (not shown) are provided for performing a normal zooming operation, and during zooming, an image of the standard object distance by the objective optical system is always displayed on the field frame 207b. Designed to be in position.

Here, the diopter adjusting device of the variable power finder having the above-mentioned structure will be described. 19 and 20,
The sliding member 311 fitted to the lens frame 310 and the driven member 312 fitted to the sliding member are shown. Figure 1
9, the center of the sliding portion 312b of the driven member 312 and the center of the cylindrical portion 312a are on the same straight line as the axial center line of the sliding member 311. In FIG. 20, the driven member 31
2 rotates around the cylindrical portion 312a, and the sliding portion 31
A moving distance D1 occurs in the optical axis direction between the center of 2a and the center line of the sliding member 311 in the axial direction. Along with that, a movement distance D2 is generated in the moving direction of the sliding member 311 at the center of the cylindrical portion 312a. The main feature of this embodiment is that the diopter adjustment is performed by adjusting the moving distance D1. As a means for rotating the driven member 312, an adjustment groove 312c is provided above the columnar portion 312a. Adjustment is performed by inserting an adjusting screwdriver into the adjusting groove 312c and rotating. The adjustment hole 313b formed in the linear guide plate 313 is for adjusting the adjustment groove 312c when the adjustment groove 312c is rotated.

As described above, the hole 31 of the sliding member 311
Cylindrical part 312a of driven member 312 press-fitted into 1a
Is fitted into the hole 311a with a frictional resistance R of a certain value or more. On the other hand, in the cylindrical portion 312a of the driven member 312,
A turning force F acts so that the lens frame drive cam plate 314 tries to rotate the cylindrical portion 312a via the sliding portion 312b. Therefore, in this embodiment, R is configured to be larger than F. With this configuration, when adjusting the diopter on the objective lens side, the diopter is adjusted by applying a force larger than the frictional resistance R to the cylindrical portion 312a and rotating the cylindrical portion 312a. In the normal zooming operation, the driven member 312 does not rotate relative to the sliding member 311. That is, the adjusted moving distance D1 is maintained, and the diopter can be adjusted on the objective optical system side. With this configuration, when the position of the image of the objective optical system deviates from the position of the field frame 207b, it can be corrected and the position of the image can be positioned on the same plane as the field frame 207b.

In the fifth and sixth embodiments described above, the first movable objective lens 202, which is the closest to the object side among the plurality of lens groups of the objective optical system, is provided with the objective side focus position adjusting means. Is not limited to this. Other specific lens groups of the plurality of lens groups of the objective optical system, or all the lens groups may be provided with the objective side focal position adjusting means.

[0033]

As described above, according to the present invention, in a viewfinder for observing an object image formed by the objective optical system through the eyepiece optical system, when the image forming position by the objective optical system is deviated from the normal position, By adjusting this, a clear image can be observed. In particular, since the position of the image of the objective optical system can be adjusted to match the position of the field frame, the field frame and the image can be observed at the same diopter.

[Brief description of drawings]

FIG. 1 is an optical system diagram showing an embodiment of a finder device according to the present invention.

FIG. 2 is a front view showing a state of shape change of the mirror of FIG. 1 depending on temperature (humidity).

FIG. 3 is an optical system diagram showing a second embodiment of the finder device according to the present invention.

FIG. 4 is an optical system diagram showing a third embodiment of the finder device according to the present invention.

FIG. 5 is an optical system diagram showing a fourth embodiment of the finder device according to the present invention.

FIG. 6 is an optical diagram in a wide end state showing a specific example of a zoom finder device.

7 is an optical diagram of the zoom finder apparatus of FIG. 6 in a telephoto end state.

8 is a graph showing how the diopter changes with the change in focal length of each lens included in the zoom finder apparatus of FIG.

9 is a graph showing how the diopter changes with the change in focal length of each lens included in the zoom finder apparatus of FIG.

FIG. 10 is a graph showing how the diopter changes with the changes in the positions of the constituent lens groups of the zoom finder device of FIG. 6;

11 is a graph showing how the diopter changes with changes in the positions of the constituent lens groups of the zoom finder apparatus of FIG. 7. FIG.

FIG. 12 is a configuration diagram of an optical system of a finder in fifth and sixth examples.

FIG. 13 is a schematic perspective external view showing a fifth embodiment of the finder device according to the present invention.

FIG. 14 is an external perspective view of the first lens frame of FIG. 13 and various elements mounted on the frame.

FIG. 15 is a perspective external view of the second lens frame in FIG.

FIG. 16 is a schematic perspective external view showing a sixth embodiment of the finder device according to the present invention.

17 is a perspective external view of the sliding member in FIG.

18 is a perspective external view of the driven member in FIG.

FIG. 19 is a plan view showing a main part of a diopter adjustment device according to a sixth embodiment.

FIG. 20 is a plan view showing a main part of a diopter adjustment device according to a sixth embodiment and showing a state different from that of FIG.

FIG. 21 is a schematic optical path diagram showing how the real image type zoom finder device changes in diopter.

[Explanation of symbols]

 10 Objective Optical System 11 Eyepiece Optical System 12 Field Frame 13 Mirror 13a Mirror Surface (Reflecting Member) 13b Substrate 13A Fixed Mirror 15 Movable Prism 16 Adjustment Frame 17, 18 Position Adjusting Means 201 Camera Body 202 First Movable Objective Lens 203 Second Movable Objective Lens 204 Third movable objective lens 205 Mirror 206 Fixed objective lens 207 Porro prism 208 Eyepiece 209 First lens frame (lens frame body) 210 Movable element 211 Second lens frame 212a Guide shaft 212b Guide shaft 213a Energizing spring 213b Energizing Spring 214 Fine adjustment male screw 215 Lens frame drive cam plate (variable magnification means) 216 Cam drive gear train 217 Drive motor 218a Support member 218b Support member 309 Lens frame holder 310 Lens frame (lens frame body) 311 Sliding member 312 Moving member 313 linearly guiding plate 314 lens frame driving cam plate (magnification means)

Front page continued (72) Inventor Hirofumi Matsuo 2-36 Maenocho, Itabashi-ku, Tokyo Asahi Kogaku Kogyo Co., Ltd. (72) Inventor Ryota Ogawa 2-36 Maeno-cho, Itabashi-ku, Tokyo Asahi Kogaku Industrial Co., Ltd. (72) Inventor Ichiro Taguchi 2-36 Maeno-cho, Itabashi-ku, Tokyo Asahi Kogaku Co., Ltd. (72) Inventor Hidetaka Yokota 2-36-9 Maeno-cho, Itabashi-ku, Tokyo Asahi Kogaku Industry Co., Ltd.

Claims (13)

[Claims] 1. A viewfinder device including an objective optical system and an eyepiece optical system, comprising an objective-side image forming position adjusting means for adjusting an image forming position of the objective optical system. apparatus. 2. The diopter adjusting device of a finder device according to claim 1, wherein the objective optical system has a positive power and has a field frame on an image forming surface thereof. 3. The objective-side image-forming position adjusting means according to claim 2, which is in the optical path from the objective optical system to the field frame, and includes an optical element that changes power according to temperature and / or humidity. Finder device diopter adjustment device. 4. The mirror according to claim 3, wherein the optical element includes a reflecting member forming a mirror surface and a substrate having a coefficient of thermal expansion or a coefficient of expansion different from that of the reflecting member bonded to the reflecting member. A diopter adjusting device for the finder device. 5. The diopter adjusting device for a finder device according to claim 2, wherein the objective-side image forming position adjusting means is an optical path length changing optical member that changes an optical path length from the objective optical system to the field frame. 6. The diopter adjusting device for a finder device according to claim 5, wherein the optical path length changing optical member is a movable reflecting member. 7. The diopter adjustment device for a finder apparatus according to claim 1, wherein the objective-side imaging position adjusting means is a total movement adjusting means for moving the entire objective optical system in the optical axis direction. 8. The objective optical system according to claim 1, wherein the objective optical system comprises a plurality of lenses, and the objective-side image-forming position adjusting means is a specific lens movement adjusting means for moving a specific lens of the plurality of lenses. A diopter adjustment device for a finder device. 9. The diopter adjustment device for a finder device according to claim 1, wherein the finder device is a variable power finder including an objective optical system having a lens group movable in the optical axis direction and an eyepiece optical system. .. 10. The finder device according to claim 9, wherein the finder device supports the movable lens group of the objective optical system, and is linearly guided in the optical axis direction; a driven member that is a member separate from the lens frame body. A diopter adjusting device for a finder device, which comprises: adjusting means for adjusting the relative position of the lens frame and the driven member in the optical axis direction; and zooming means for moving the driven member in the optical axis direction. 11. The diopter adjusting means according to claim 10, which is a movable element provided in a lens frame body supporting the movable lens group and capable of finely moving in the optical axis direction, and a distance relative to the driven member. A diopter adjustment device for a finder device that can maintain a constant value. 12. The finder device according to claim 9, wherein the finder device supports the movable lens group of the objective optical system and is linearly guided in the optical axis direction; a driven member which is linearly guided in the optical axis direction; Magnification changing means for moving the driven member in the optical axis direction; a sliding member provided on the lens frame body and movable in a direction orthogonal to the optical axis with respect to the lens frame body; A diopter adjusting device for a finder device, comprising: adjusting means for adjusting the relative distance of the means in the optical axis direction. 13. The diopter according to claim 10 or 12, wherein the zooming means is a plate-shaped movable element driven by a drive motor, and a cam groove formed in the element drives the driven member. Adjustment device.